Re: [Xen-devel] [PATCH v5 18/25] xen/arm: generate vpl011 node on device tree for domU

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 10/23/18 3:02 AM, Stefano Stabellini wrote:
> Introduce vpl011 support to guests started from Xen: it provides a
> simple way to print output from a guest, as most guests come with a
> pl011 driver. It is also able to provide a working console with
> interrupt support.
>
> The UART exposed to the guest is a SBSA compatible UART and not a PL011.
> SBSA UART is a subset of PL011 r1p5. A full PL011 implementation in Xen
> would just be too difficult, so guests may require some drivers changes.
>
> Enable vpl011 conditionally if the user requested it.
>
> Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
> Changes in v5:
> - use dt_property_read_bool
>
> Changes in v4:
> - move rename set_interrupt_ppi and making set_interrupt_ppi generic to
>    a separate patch
> - properly name the vpl011 device node name
> - code style
> - use #define for addrcells and sizecells
>
> Changes in v3:
> - use bool
> - retain BUG_ON(irq < 16)
> - add vpl011 bool to kinfo
> - return error of vpl011 is required but CONFIG_SBSA_VUART_CONSOLE is
>    missing
>
> Changes in v2:
> - code style fixes
> - make set_interrupt_ppi generic
> - rename set_interrupt_ppi to set_interrupt
> - only make the vpl011 node if the option was enabled
> ---
>   xen/arch/arm/domain_build.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
>   xen/arch/arm/kernel.h       |  3 +++
>   2 files changed, 63 insertions(+)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index a7fd4f1..6026b77 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1620,6 +1620,54 @@ static int __init make_timer_domU_node(const struct 
> domain *d, void *fdt)
>       return res;
>   }
>   
> +#ifdef CONFIG_SBSA_VUART_CONSOLE
> +static int __init make_vpl011_uart_node(const struct domain *d, void *fdt)
> +{
> +    int res;
> +    gic_interrupt_t intr;
> +    __be32 reg[GUEST_ROOT_ADDRESS_CELLS + GUEST_ROOT_SIZE_CELLS];
> +    __be32 *cells;
> +
> +    res = fdt_begin_node(fdt, "sbsa-uart@"__stringify(GUEST_PL011_BASE));
> +    if ( res )
> +        return res;
> +
> +    res = fdt_property_string(fdt, "compatible", "arm,sbsa-uart");
> +    if ( res )
> +        return res;
> +
> +    cells = &reg[0];
> +    dt_child_set_range(&cells, GUEST_ROOT_ADDRESS_CELLS,
> +                       GUEST_ROOT_SIZE_CELLS, GUEST_PL011_BASE,
> +                       GUEST_PL011_SIZE);
> +    if ( res )
> +        return res;
> +    res = fdt_property(fdt, "reg", reg, sizeof(reg));
> +    if ( res )
> +        return res;
> +
> +    set_interrupt(intr, GUEST_VPL011_SPI, 0xf, DT_IRQ_TYPE_LEVEL_HIGH);
> +
> +    res = fdt_property(fdt, "interrupts", intr, sizeof (intr));
> +    if ( res )
> +        return res;
> +
> +    res = fdt_property_cell(fdt, "interrupt-parent",
> +                            GUEST_PHANDLE_GIC);
> +    if ( res )
> +        return res;
> +
> +    /* Use a default baud rate of 115200. */
> +    fdt_property_u32(fdt, "current-speed", 115200);
> +
> +    res = fdt_end_node(fdt);
> +    if ( res )
> +        return res;
> +
> +    return 0;
> +}
> +#endif
> +
>   /*
>    * The max size for DT is 2MB. However, the generated DT is small, 4KB
>    * are enough for now, but we might have to increase it in the future.
> @@ -1681,6 +1729,16 @@ static int __init prepare_dtb_domU(struct domain *d, 
> struct kernel_info *kinfo)
>       if ( ret )
>           goto err;
>   
> +    if ( kinfo->vpl011 )
> +    {
> +        ret = -EINVAL;
> +#ifdef CONFIG_SBSA_VUART_CONSOLE
> +        ret = make_vpl011_uart_node(d, kinfo->fdt);
> +#endif
> +        if ( ret )
> +            goto err;
> +    }
> +
>       ret = fdt_end_node(kinfo->fdt);
>       if ( ret < 0 )
>           goto err;
> @@ -2549,6 +2607,8 @@ static int __init construct_domU(struct domain *d,
>   
>       printk("*** LOADING DOMU cpus=%u memory=%luKB ***\n", d->max_vcpus, mem);
>   
> +    kinfo.vpl011 = dt_property_read_bool(node, "vpl011");
> +
>       if ( vcpu_create(d, 0, 0) == NULL )
>           return -ENOMEM;
>       d->max_pages = ~0U;
> diff --git a/xen/arch/arm/kernel.h b/xen/arch/arm/kernel.h
> index 4320f72..33f3e72 100644
> --- a/xen/arch/arm/kernel.h
> +++ b/xen/arch/arm/kernel.h
> @@ -33,6 +33,9 @@ struct kernel_info {
>       paddr_t dtb_paddr;
>       paddr_t initrd_paddr;
>   
> +    /* Enable pl011 emulation */
> +    bool vpl011;
> +
>       /* loader to use for this kernel */
>       void (*load)(struct kernel_info *info);
>       /* loader specific state */
--
Julien Grall

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